Basic character of amines in non-gaseous phase or in polar solvent is explained on the basis of which factor(s)

The basic strength of amines in polar solvent (or) non-gaseous phase will be explained by summation of three factors 1) Inductive effect (Acc to this the order of basicity is  -amine >  -amine > -amine> NH3)2) Solvation effect  α1size of the amineRNH2>R2NH>R3N3) According to Steric hindrance the order of basicity of amines is  20>10>30